1. Field of the Invention
This invention relates to a network configuration control method and a network configuration control unit, and specifically relates to the network configuration control method and the network configuration control unit that realize network configuration by reservation.
2. Description of the Related Art
In order to configure a network by reservation, operation of network transmission apparatuses have to be controlled based on a reservation process. In order to configure the operation of a network transmission apparatus, the apparatus was directly operated manually in earlier days. Later, an operation system emerged, which supervises and controls the apparatus efficiently, and the apparatus can now be configured by a screen operation from a remote place.
Relations between network composition and a path and a circuit are shown in FIG. 1, which provide a basis for an understanding of descriptions that will follow. We shall consider an example wherein subscribers T of Tokyo (starting point) 30, and subscribers O of Osaka (terminal point) 37 are connected by a circuit. The subscribers T and the subscribers O are connected to transmission apparatuses (NE) 31 and 36, respectively, via a circuit 38 to adjacent telephone offices T and O, respectively. There are many telephone offices (for example, xx through xx) in the network, each of which has a transmission apparatus (NE), similar to the telephone offices T and O, for structuring a circuit. The telephone offices are connected by a path. Here, the path is a collection of circuits (it can also be called a bundle of circuits). A connection between the subscribers T and the subscribers O is established by accommodating the circuit 38 into a path at the telephone office T and the telephone office O, and by connecting the telephone offices T and O by a path via a number of other telephone offices (xx through xx). Further, FIG. 1 can also be regarded as showing a common carrier leased line which accommodates a plurality of circuits laid between the telephone office T and the telephone office O. In this manner, the subscribers T and the subscribers O mutually communicate using one of the common carrier leased lines.
FIG. 2 is a drawing for explaining configuration to accommodate a path and a circuit. In order to accommodate the circuit in the path, 3 configurations are performed, namely,                (1) deciding a user's service item at an accommodating office, wherein, the user's service item means bandwidth (64 kbps, 2 Mbps, etc.) and the like that the subscriber uses,        (2) deciding on which path the circuit is to be accommodated among paths connected to the accommodating office, and        (3) performing the similar configuration in each telephone office that is included such that a required network is established by connecting paths connected to the accommodating office and the included offices that relay a communication.        
Here, such configuration of a path and a circuit as above is called an “opening”. Another configuration is a “closing”. The “closing” is the opposite of the “opening”, that is, an opened network is returned to an initial status. Further, a duration while a network is open is called “in operation”, and a duration while the network is closed is called “not in operation”.
FIG. 3 shows an outline of a system for configuration control, which performs openings and closings on a network. A plurality of telephone offices and a plurality of transmission apparatuses 9 are connected between the telephone office T and the telephone office O. Each transmission apparatus 9 is equipped with an NE-DB which is an operational database into which configuration information on the transmission apparatus is stored. Further, a configuration control system of each office includes an operational DB10 that stores information about all NE-DBs of the office. According to contents of the operational DB10, the NE-DB in each transmission apparatus is modified to configure that transmission apparatus.
Here, instead of each transmission apparatus 9 being equipped with the configuration control system, a system may be structured such that one control system centrally controls the plurality of the transmission apparatuses 9 between the office T and the office O as a group.
In the telephone office T and the telephone office O, a path-circuit configuration direction means 7T and 7O, respectively, outputs a configuration direction of a path and a circuit. Operational DB 10T and 10O are updated according to the direction. Information stored in the operational DB 10T and 10O is immediately reflected to the NE-DB in the appropriate transmission apparatuses, and a network is configured.
However, since the network configuration is reflected to the network immediately after the configuration is provided to the operational DB, there is a problem that a vast amount of work is concentrated just before time to configure, in the case where a major configuration process has to be carried out.
In order to eliminate the vast amount of work required at time of configuration, a configuration control system that beforehand reserves contents of a configuration beforehand has been developed.
FIG. 4 shows a conventional configuration control system that performs using a reservation process. FIG. 4 includes offices 1 and 2, an operational database (operational DB) 10, a reservation information database (reservation information DB) 11, a time determining processing means 16, a reservation processing means 17, and a reservation directing means 18. Transmission apparatuses (NE 151 and 152) are provided in the office 1 as an example.
The operational DB 10 stores configuration information about network operations. A circuit and a path of the transmission apparatus are configured based on this configuration information. The reservation information DB 11 stores reservation information. The time determining processing means 16 checks reservation times and when a reservation time is reached, it performs the required processing to effect changes in network configuration. The reservation processing means 17 is a means to create reservations. The reservation directing means 18 directs contents of reservations to appropriate DBs. The NE 151 and 152 are transmission apparatuses at which a reservation is targeted.
As shown in the drawing, the configuration information that is to be used for network operations is set up in the reservation information DB 11 by the reservation processing means 17, which is then included in the contents of the directions that the reservation directing means 18 outputs. When the time determining processing means 16 determines that the reservation time has arrived, configuration contents stored in the reservation information DB 11 are provided to the operational DB10. Information provided to the operational DB10 is reflected as it is to the NE 151 and NE 152.
The conventional technology is explained using FIG. 5. The structure of the reservation of the conventional technology is as follows.
An opening reservation is accepted in the reservation information DB 11 when a route between a starting point and a terminal point is not in operation nor already reserved for opening as of the time of the opening reservation.
Further, a closing reservation is accepted in the reservation information DB 11 when a route between the starting point and the terminal point is in operation, or already reserved for opening. In the case of the closing reservation of a reserved opening, a check is performed to ascertain that the closing will take effect after the opening.
In FIG. 5A, examples are presented of a path in operation (B1-B2-A3-C4) and paths under opening reservation (C1-C2 and B3-B4) at time T.
Here, suppose that an opening reservation as shown in FIG. 5B (A1-A2-C3-A4) is scheduled for time T+α. The opening reservation is accepted because, as seen from FIG. 5A and FIG. 5B, the path A1-A2-C3-C4 for the opening reservation is not in operation nor already reserved at the time T.
Further, in FIG. 5, a closing reservation with path B1-B2-A3-A4 is accepted unconditionally. A closing reservation with path C1-C2-B3-B4 is accepted only when time to close is after the time T+α.
Now, the opening reservation of A1-A2-C3-A4 is to be performed (FIG. 5B). An operator gives the reservation processing means 17 information about the starting point, the terminal point, and reservation time using the reservation directing means 18. As the drawing shows, the reservation time T+α, and the three pieces of information, namely the starting points and the terminal points, “A1 and A2”, “A2 and C3” and “C3 and A4”, respectively, are provided, thereby the opening reservation of A1 through A4 is created. The reservation processing means 17 checks whether paths between each of the starting point and each of the terminal point of the three reservations are available, that is, not in operation nor already reserved, making a reference to the reservation information DB 11. If the check was affirmative, the new reservation is added to DB 11. If the check was negative, the opening reservation of A1-A2-C3-A4 is not added to DB 11. Further, in the case where a closing reservation is processed for a certain starting point through a terminal point, the reservation processing means 17 makes a reference to the reservation information DB 11 to determine that the starting point through the terminal point is either in operation or already reserved for opening before adding the closing reservation. In the case of an existing opening reservation, a check is performed to ascertain that the closing will take place after the opening.
Thus, the conventional technology stores a configuration beforehand and performs processing at a desired time. However, a problem is that a new reservation for a near future is rejected if there is an opening/closing reservation of a given network section already set up for a far future, even if the new reservation would be acceptable.
For example, if a path as shown in FIG. 6A has been reserved between the telephone offices O and T (reservation time T4), and if opening and closing of a path between the telephone offices Y and T has been reserved for a period between T2 and T3 as shown in FIG. 6B, a reservation of a path for part or all of sections between the telephone office O and T for a time period from a present time T1 to a time T2 is not allowed.
This problem denies the effective use of resources by a communication carrier.
To avert this problem, it is conceived that a first reservation is temporarily cancelled, a near future reservation is performed, and upon completion of the near future reservation, the first reservation is restored. However, this causes a problem in that it is troublesome and inefficient.
Further, since the conventional technology does not provide a means to take a change in operational situations into account regarding reservation management when emergency configuration work is performed without regard to reservations, a problem is that an error may occur in reservations that follow.